04 Suburban Heater not working at idle


Old 11-25-12, 02:41 PM
Thread Starter
Join Date: Aug 2006
Location: iowa
Posts: 52
04 Suburban Heater not working at idle

Our 04 suburban has shown this chronic issue. It will not kick out any heat to the cabin until we get moving or the engine is run at a higher RPM. The level of coolant is normal. Once we get going it seems to heat and do its job but in IA in the winter it will not clear the frost off the windshield during warm up in the driveway. The engine heat is reading near near the 200 mark.

Any ideas? If there is air in the system forming a "vapor lock" what is the best way of assure the air is out of the system and stays out.

Thanks for your help.

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Old 11-25-12, 03:07 PM
ukrbyk's Avatar
Join Date: Mar 2010
Location: USA/ Pacific NW
Posts: 3,191
Your Burban and my Silverado sharing same platforms. My 5.8L V8 does take sweet time to warm up, that it does.
How many miles? Serpentine is supposed to be done at 100K, hence, if it's stretched, it is not moving water pump well enough.
Your T-stat might be stuck open.
Best bet is to warm up engine in one of the D gears, as that puts some strain on it and produces faster warm up.
If you can, check both hoses, upper and lower rad ones, for temp consistency. Just be careful, don't burn yourself. In your case - they both should be uniformly HOT. Then, check heater core hoses, they should be same way. It is quite common for heater cores to get plugged, esp if one had leaking radiator and put one of those Stop Leak things in.
Last but not least - your coolant pump might be getting there.

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